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BioMed Research International
Volume 2016 (2016), Article ID 7326160, 10 pages
Research Article

The Effect of Altitude on Intraocular Pressure in Vitrectomized Eyes with Sulfur Hexafluoride Tamponade by the Friedenwald Method: Rabbit Animal Model

Retina Department, Asociación para Evitar le Ceguera en México IAP, 04030 México City, Mexico

Received 5 July 2016; Revised 7 October 2016; Accepted 11 October 2016

Academic Editor: Mitsuru Nakazawa

Copyright © 2016 Jans Fromow-Guerra et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this study is to assess the change in intraocular pressure after a road trip, in eyes with different levels of filling with gas tamponade. Five rabbit eyes were subject to pars plana vitrectomy and gas tamponade (filling percentage: 25%, 50%, and 100% of nonexpansile SF6, 100% saline solution, and 100% room air). A sixth eye was injected with 0.35 cc of undiluted SF6 without vitrectomy. Guided by global positioning system, they were driven to the highest point of the highway connecting Mexico City with Puebla city and back, stopping every 300 m to assess intraocular pressure. The rabbit’s scleral rigidity and estimation for human eyes were done by using the Friedenwald nomogram. Maximum altitude was 3209 m (Δ949 m). There were significant differences in intraocular pressure on the rabbit eyes filled with SF6 at 100%, 50%, 25%, and 100% room air. Per every 100 m of altitude rise, the intraocular pressure increased by 1.53, 1.0046, 0.971, and 0.97 mmHg, respectively. Using the human Friedenwald rigidity coefficient, the human eye estimate for intraocular pressure change was 2.1, 1.8, 1.4, and 1.1 mmHg per every 100 m of attitude rise. Altitude changes have a significant impact on intraocular pressure. The final effect depends on the percentage of vitreous cavity fill and scleral rigidity.